rbldnsd is a small and fast DNS daemon which is especially made to serve
DNSBL zones. This daemon was inspired by Dan J. Bernstein's rbldns
program found in the djbdns package.

rbldnsd is extremely fast - it outperforms both bind and djbdns greatly.
It has very small memory footprint.

The daemon can serve both IP-based (ordb.org, dsbl.org etc) and
name-based (rfc-ignorant.org) blocklists. Unlike DJB's rbldns, it has
ability to specify individual values for every entry, can serve as many
zones on a single IP address as you wish, and, finally, it is a real
nameserver: it can reply to DNS metadata requests. The daemon keeps all
zones in memory for faster operations, but its memory usage is very
efficient, especially for repeated TXT values which are stored only
once.
